Many ideas have been applied to solve the problem of a person with impaired vision, such as either near-sightedness or far-sightedness, to aim a firearm. Aiming, for example, a rifle equipped with open sights requires that the person simultaneously visualize a rear sight, a front sight, and the target. The rear sight may be an open iron sight at about 12 inches to 18 inches from the person's eye. The front sight is another approximately 2 to 3 feet further away, near the muzzle of the rifle. The target is at optical infinity, perhaps a few hundred feet to several thousand yards away. A person who cannot properly accommodate the lens of his/her eye to focus simultaneously to the rear sight, the front sight, and the target is unable to accurately aim the rifle.
For example, telescopes have been adapted as sighting devices for rifles. The telescope receives light rays at its objective lens which have been reflected by the target. The path of the light rays is appropriately modified by lenses of the telescope, and exit from the eyepiece of the telescope. The person adjusts the focus of the telescope so that he can simultaneously visualize both a cross hair located in the telescope and the target. The telescope is aligned with the rifle so that when the cross hair appears to coincide with the target, the flight of the bullet will follow a substantially Galilean trajectory (allowance being made for air resistance) and strike the target at the spot indicated by the intersection of the cross hairs. However, a telescope is a complicated attachment to a rifle, and so does not solve the problem of using open sights by a person who is unable to simultaneously visualize a rear open sight, a front sight, and the target. Further, telescope sights are expensive, and when a person owns several rifles, the cost of a telescope sight for each becomes prohibitive.
Peep hole sights have been tried as solutions to the problem of simultaneous visualization of a rear sight, a front sight, and a target for aiming a rifle. A typical prior art peep hole sight is shown in FIG. 1. A small hole 2 in a metal plate 4 is positioned to serve as a rear sight. A small hole used as a sight is often referred to as a “peep hole sight”. A peep hole sight as shown in FIG. 1 is often referred to as a tang-mounted peep hole sight.
A suction cup has been used to attach a peep hole sight to eyeglasses, as shown in FIG. 2A and FIG. 2B. Both transparent (shown in FIGS. 2A and 2B) and opaque (not shown) suction cups have been used. The suction cups refract light and are very distracting to the person trying to aim the firearm. Suction cup 3 adheres to lens of eyeglasses 7 by atmospheric pressure pressing to fill a vacuum between suction cup 3 and lens of eyeglasses 7. Peep hole sight 9 is held onto eyeglasses by suction cup 3, and ultimately by atmospheric pressure holding suction cup 3 onto lens of eyeglasses 7. Peep hole sight 9 has a portion 5 which surrounds a portion of suction cup 3, and so binds the peep hole sight 9 to the suction cup 3.
Vision impaired individuals are assisted in driving an automobile by attachment of a small telescope 13 to ordinary eyeglasses, as shown in FIG. 3A, and the small telescope may be called a “BIOptic”. FIG. 3B shows a group of fitting apertures used in preparing a BIOptic for a patient. The numbers 14, 16, 19, 22, 24, 27, and 33 beside the apertures indicate the diameter of the apertures. Placement of the fitting aperture on eyeglasses is shown in FIG. 3C. Fitting a BIOptic to a patient is shown in FIG. 3G and FIG. 3H, including the use of a protractor with a fitting aperture to measure a mounting angle for a BIOptic.
When a firearm is equipped with open sights, such as a “notch” type rear sight and a “post” type front sight, a person who is either near-sighted or far-sighted has difficulty, and often finds it impossible, to visualize both the rear sight and the front sight, along with the intended target. Accordingly, the person has great difficulty in aiming the firearm.
The problem of a person with impaired vision, such as either nearsightedness or far-sightedness, to aim a firearm equipped with open sights has not been solved.